Yeah, there's a lot that Nunnally could bring up if she chose to. XD Lelouch is sort of expecting to have a couple of difficult conversations with her sooner or later because he's not sure how much she knows of the truth, but he's pretty sure she doesn't have all of it. One thing he does not want to talk about is their parents, though, because he's really reluctant to shatter her memories of their mother unless there's some need for him to do so.